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1.
The complex relation between the genotype of Helicobacter pylori and its association with clinical outcome is not well understood. Studies in the West have showed that strains expressing certain virulence factors (vacAs1, vacAm1, and cagA) are associated with duodenal ulcer disease. However, the H. pylori genotype is known to vary with geographic region. In the present study, we compared several virulence markers (cagA, vacA, and iceA) and neutral markers (IS605, IS606, and IS608) in H. pylori strains isolated from 65 adult patients with peptic ulcer (PU) and 50 patients with nonulcer dyspepsia (NUD). PCR tests indicated that cagA is present in 75% of the strains from patients with PU compared to 55% in patients with NUD, and 80% of the isolates from patients with PU carried potentially toxigenic vacAs1 alleles of the vacuolating cytotoxin gene (vacA) compared to 60% in isolates from patients with NUD. However, no significant difference in any other virulence marker was observed in isolates from both groups. Phylogenetic analysis of the vacA middle region and the 5' end of the cagA gene indicates that Bangladeshi isolates are more closely related to H. pylori isolates from India and are different from isolates from East Asia.  相似文献   

2.
Han F  Liu S  Ho B  Yan Z  Yan X 《Research in microbiology》2007,158(1):38-44
Metronidazole resistance among Helicobacter pylori strains has been related to alterations in gene products having metronidazole nitroreductase activities. RdxA and FrxA proteins are the two major contributing factors. In this investigation, the rdxA and frxA genes and their upstream regions were analyzed in 19 H. pylori isolates, 8 of which were metronidazole-sensitive (MIC < or = 8 microg/mL) and 11 of which were metronidazole-resistant (MIC > or = 8 microg/mL), as determined by the E-test. Among the metronidazole-resistant isolates, three contained both RdxA and FrxA proteins with premature truncation caused by gene nonsense mutations or frameshift mutations, while three contained only stop mutations in FrxA and two only in RdxA. Substitutions of amino acids occurred in other RdxA (5/6) and FrxA (4/5) proteins from metronidazole resistant isolates as compared with those from metronidazole-sensitive ones. All metronidazole-resistant isolates had alterations in RdxA and/or FrxA proteins. Moreover, the upstream regions (-1 to -35) of rdxA and frxA genes in some metronidazole-resistant isolates varied by nucleotide insertion and/or deletion or substitution. The patterns of variation in both genes and their upstream regions were highly diversified. Alterations in rdxA and frxA genes and their upstream regions may be involved in the development of metronidazole resistance in H. pylori.  相似文献   

3.
The aim of this study was to evaluate the primary and combined resistance of Helicobacter pylori against four antimicrobial agents by a screening agar method (SAM) and a modified disk diffusion method (MDDM) alone and in combination. Pre-treatment H. pylori isolates from 192 consecutive H. pylori-positive patients at three hospitals in Sofia were investigated. MDDM was performed with disks containing metronidazole (5 microg), clarithromycin (15 microg) or erythromycin (15 microg), ciprofloxacin (5 microg) and tetracycline (30 microg). Resistance was determined by an inhibitory zone of <16 mm for metronidazole and < or =30 mm for other agents tested. The cut-off concentrations used to define resistance by SAM were: metronidazole >8 mg/L, clarithromycin >2 mg/L, tetracycline >4 mg/L and ciprofloxacin >1 mg/L. Primary resistance rates in H. pylori were: metronidazole 28.6%, clarithromycin 9.7%, metronidazole + clarithromycin 2.8%, ciprofloxacin 3.9%, metronidazole + ciprofloxacin 2.3%, tetracycline 1.9% and metronidazole + tetracycline 1.2%. Among metronidazole-resistant isolates, combined resistance to clarithromycin, ciprofloxacin and tetracycline was present in 11.4% (5 of 44 strains), 8.3% (3 of 36) and 4.9% (2 of 41), respectively. Two strains exhibited triple resistance to macrolides, metronidazole and either ciprofloxacin or tetracycline. Three tetracycline-resistant strains were detected in 1999; however, resistance rates to other agents were relatively stable during the 6 years. Primary H. pylori resistance to metronidazole is moderate and resistance to clarithromycin and to ciprofloxacin is considerable in comparison with results in most other countries. The alarming appearance of strains harbouring combined resistance or multiresistance provides the motivation for continued surveillance of H. pylori at global, national and regional levels.  相似文献   

4.
OBJECTIVE: To determine the prevalence and disease association of Helicobacter pylori (H. pylori) in dyspeptic patients in southwest Nigeria. Setting: Obafemi Awolowo University Teaching Hospitals Complex, Ile-lfe, Nigeria. METHODS: Consecutive dyspeptic patients for upper gastrointestinal endoscopy from January 1996 to March 1997 were investigated for H. pylori in gastric biopsy by histopathology and culture. Patients without gastroduodenal ulcerations or neoplastic lesions constituted the nonulcer dyspeptic (NUD) group. RESULTS: 138 (92 males, 46 females) patients aged 4.5-85 years [mean (7) = 45+/-SD 17.8 years] who had upper gastrointestinal endoscopy were analyzed for presence of H. pylori. Eighty-three had histopathology alone, while 55 others had both histology and culture. Endoscopic diagnosis included duodenal ulcer (DU) (n=35, 23%); gastric ulcer (n=4, 3%); gastric cancer (n=14, 9%); NUD, including gastritis (n=49, 32%); duodenitis (n=47, 31%); and normal (n=16, 11%). Overall, H. pylori was positive in 107 of 138 (77.5%) patients. There was a significant association of H. pylori with DU and NUD (p<0.000). Three-quarters of cases of normal endoscopy harbored H. pylori. The finding of 80% and 85% H. pylori in gastritis and duodenitis, respectively, was of interest. CONCLUSIONS: These findings suggest that DU and NUD were the main clinical expressions of H. pylori infection in southwest Nigerian dyspeptic patients similar to what is found in developed nations. Of note is the high incidence of H. pylori in endoscopically normal patients.  相似文献   

5.
Prevalence of resistant Helicobacter pylori isolates in Bulgarian children   总被引:3,自引:0,他引:3  
The aim of this study was to assess the primary and combined resistances of Helicobacter pylori isolates obtained from paediatric patients in 2000-2001 to seven antimicrobial agents. Resistance rates of pre-treatment isolates from 115 children were investigated by the limited agar dilution method alone and by the E-test. The cut-off concentrations for resistance were: metronidazole >8 mg/L, clarithromycin and azithromycin >1 mg/L, clindamycin >4 mg/L, amoxicillin >0.5 mg/L, tetracycline >4 mg/L and ciprofloxacin >1 mg/L. Primary resistance rates were: metronidazole 15.8%, clarithromycin 12.4%, azithromycin 14.6%, clindamycin 20.0%, amoxicillin 0%, metronidazole + clarithromycin 4.5%, ciprofloxacin 6.0%, metronidazole + clarithromycin + ciprofloxacin 1.2%, tetracycline 3.1% and metronidazole + ciprofloxacin 1.2%. There were no significant age (1-9 years versus 10-18 years) or gender differences. Prevalence of both macrolide-resistant and intermediately susceptible strains was 21.9% for azithromycin and 15.9% for clarithromycin. Of 18 metronidazole-resistant isolates, 77.8% exhibited a metronidazole MIC > or = 32 mg/L. H. pylori resistance rates to metronidazole, clarithromycin and both agents were relatively low in Bulgarian children. However, resistance was found to all drugs tested except for amoxicillin. The consumption of newer macrolides and tetracyclines could be related to the prevalence of resistance to the corresponding agents. There were no significant differences in primary resistance rates of H. pylori to antimicrobial agents between children and adults except for metronidazole. Multi-drug resistance to newer macrolides, metronidazole and ciprofloxacin in association with a slightly elevated amoxicillin MIC (0.38 mg/L) was detected in one strain.  相似文献   

6.
PURPOSE: To assess the pattern of antimicrobial susceptibility profile of Helicobacter pylori isolates from patients with gastritis, duodenal ulcer (DU) and gastroesophageal reflux disease (GERD) residing in Shiraz, Iran. METHODS: One hundred and six H. pylori isolates from patients with gastritis, DU and GERD undergoing endoscopy at our university hospitals and clinics were analysed for their antimicrobial susceptibility to metronidazole, clarithromycin, amoxicillin, co-amoxiclav, tetracycline, ciprofloxacin and furazolidone. The minimum inhibitory concentrations were determined by agar dilution method. RESULTS: Overall H. pylori resistance rate was 72.6% to metronidazole, 9.4% to clarithromycin and furazolidone, 20.8% to amoxicillin and 4.7% to tetracycline and ciprofloxacin. No resistance to co-amoxiclav was detected among H. pylori isolates. No significant differences between antimicrobial resistance and clinical outcome were detected. CONCLUSIONS: With regard to the increasing resistance of H. pylori isolates to various antibiotics, susceptibility testing of H. pylori isolates prior to the treatment of infection must be performed to achieve better eradication and to reduce the risk of selection of H. pylori resistant strains.  相似文献   

7.
Approximately 60% of Helicobacter pylori isolates possess the cagA gene and express its 120- to 140-kDa product (CagA). In this study, the cagA gene was detected in H. pylori isolates from 26 (81.3%) of 32 patients with duodenal ulcers (DU), 17 (68.0%) of 25 patients with gastric ulcers, and 23 (59.0%) of 39 patients with nonulcer dyspepsia (NUD). By Western blotting (immunoblotting) with antiserum to CagA, in vitro CagA expression was demonstrated for 95.5% of cagA+ strains compared with 0% of strains lacking cagA. Sera from patients infected with cagA+ strains (n = 66) reacted with recombinant CagA in an enzyme-linked immunosorbent assay to a significantly greater extent than either sera from patients infected with strains lacking cagA (n = 30) or sera from uninfected persons (n = 25) (P < 0.001). A strain lacking cagA was isolated from eight patients who had serum immunoglobulin G antibodies to CagA, which suggests that these patients were infected with multiple strains. Serum immunoglobulin G antibodies to CagA were present in 87.5, 76.0, and 56.4% of patients with DU, gastric ulcers, and NUD, respectively (odds ratio, 5.41; 95% confidence interval, 1.44 to 24.72; P = 0.004 [DU versus NUD]). These data demonstrate an association between infection with cagA+ H. pylori and the presence of duodenal ulceration and indicate that serologic testing is a sensitive method for detecting infection with cagA+ strains.  相似文献   

8.
Metronidazole-susceptible pretreatment isolates and metronidazole-resistant posttreatment isolates of Helicobacter pylori from 11 patients before and after unsuccessful triple therapy consisting of metronidazole, amoxicillin, and colloidal bismuth subcitrate were studied. Ribotyping (rRNA gene restriction pattern analysis) of the isolates demonstrated that all patients except one had identical digest patterns for pre- and posttreatment isolates.  相似文献   

9.
Antimicrobial resistance in Helicobacter pylori is a serious and increasing problem, and the development of rapid, reliable methods for detecting resistance would greatly improve the selection of antibiotics used to treat gastric infection with this organism. We assessed whether detection of the RdxA protein could provide the basis for determining the susceptibility of H. pylori to metronidazole. In order to raise polyclonal antisera to RdxA, we cloned the rdxA gene from H. pylori strain 26695 into the commercial expression vector pMAL-c2, purified the resultant fusion protein by affinity chromatography, and used this recombinant RdxA preparation to immunize rabbits. We then used this specific anti-RdxA antibody to perform immunoblotting on whole bacterial cell lysates of 17 metronidazole-sensitive and 27 metronidazole-resistant clinical isolates of H. pylori. While a 24-kDa immunoreactive band corresponding to the RdxA protein was observed in all metronidazole-sensitive strains, this band was absent in 25 of 27 resistant isolates. Our results indicate that testing for the absence of the RdxA protein would identify the majority of clinical isolates that will respond poorly to metronidazole-containing eradication regimens and have implications for the development of assays capable of detecting metronidazole resistance in H. pylori.  相似文献   

10.
Helicobacter pylori infection is more common in Alaska Native persons than in the general U.S. population, with seroprevalence to H. pylori approaching 75%. Previous studies in Alaska have demonstrated elevated proportions of antimicrobial resistance among H. pylori isolates. We analyzed H. pylori data from the Centers for Disease Control and Prevention's sentinel surveillance in Alaska from January 2000 to December 2008 to determine the proportion of culture-positive biopsy specimens with antimicrobial resistance from Alaska Native persons undergoing endoscopy. The aim of the present study was to monitor antimicrobial resistance of H. pylori isolates over time and by region in Alaska Native persons. Susceptibility testing of H. pylori isolates to metronidazole, clarithromycin, amoxicillin, and tetracycline was performed using agar dilution. Susceptibility testing for levofloxacin was performed by Etest. Overall, 45% (532/1,181) of persons undergoing upper endoscopy were culture positive for H. pylori. Metronidazole resistance was demonstrated in isolates from 222/531 (42%) persons, clarithromycin resistance in 159/531 (30%) persons, amoxicillin resistance in 10/531 (2%) persons, and levofloxacin resistance in 30/155 (19%) persons; no tetracycline resistance was documented. The prevalence of metronidazole, clarithromycin, and levofloxacin resistance varied by region. Female patients were more likely than male patients to demonstrate metronidazole (P < 0.05) and clarithromycin (P < 0.05) resistance. No substantial change in the proportion of persons with resistant isolates was observed over time. Resistance to metronidazole, clarithromycin, and levofloxacin is more common among H. pylori isolates from Alaska Native persons than those from elsewhere in the United States.  相似文献   

11.
Antimicrobial susceptibility of 120 Helicobacter pylori isolates to metronidazole, tetracycline, clarithromycin, and amoxicillin was determined, and 77.5, 15, 10, and 6.6% of the isolates, respectively, were resistant. Only rdxA inactivation and both rdxA and frxA inactivation were responsible for metronidazole resistance in 66% (8 of 12) and 33% (4 of 12) of the isolates, respectively.  相似文献   

12.
The issue of antibiotic resistance in Helicobacter pylori is of particular concern and has become an important factor leading to eradication failure. This paper reports the prevalence of primary resistance to clarithromycin, amoxicillin, metronidazole and tetracycline among H. pylori isolates in the north-eastern part of Germany. A total of 1644 clinical H. pylori isolates was investigated over a period of 6 years from 1995 to 2000. The MICs were determined by the Etest. The overall rate of primary resistance was 26.2% for metronidazole and 2.2% for clarithromycin. No significant changes in the resistance rates during the period of investigation were observed. No isolate was resistant to amoxicillin or tetracycline. PCR-RFLP analysis for the detection of point mutations associated with clarithromycin resistance was performed with 36 H. pylori isolates. The A --> G transition mutation at position 2143 was detected in 19 H. pylori isolates (52.8%), whereas the mutation at position 2142 was found in 13 isolates (36.1%).  相似文献   

13.
Antimicrobial susceptibility testing was performed on 48 isolates of Helicobacter pylori recovered from Egyptian children undergoing routine endoscopies. The isolates were universally highly resistant to metronidazole, but resistance to other tested antimicrobial agents was rare (4% for clarithromycin, erythromycin, and azithromycin resistance versus 2% for ciprofloxacin and ampicillin resistance). Use of metronidazole for the treatment of H. pylori in Egypt should be avoided.  相似文献   

14.
BACKGROUND: Resistance of Helicobacter pylori to the more frequently used antibiotics (metronidazole and clarithromycin) reduces eradication rates even with triple treatment. Determining the antibiogram profile of H pylori can take up to 14 days and delays appropriate treatment. AIMS: To determine the role of screening agar plates for more rapid in vitro susceptibility of H pylori to metronidazole, amoxicillin, and clarithromycin. METHODS: Routine gastric biopsy specimens from 507 dyspeptic patients were inoculated on to 10% lysed blood agar plates containing metronidazole (8 microg/ml), clarithromycin (2 microg/ml), or amoxicillin (0.5 microg/ml). The minimum inhibitory concentration (MIC) of the 90 isolates was determined using the E test. RESULTS: Metronidazole resistance was detected in 28 of 90 isolates by E test and nine of 98 by screening agar. The screening agar detected none of the four clarithromycin resistant isolates detected by the E test. CONCLUSIONS: The screening agar method is not sufficiently sensitive to be used alone.  相似文献   

15.
Thirty patients with dyspepsia, with histological diagnosis of gastritis, and with endoscopic diagnosis of peptic ulcer disease (PUD) (n = 13) or nonulcer dyspepsia (NUD) (n = 17) were admitted to the study. Helicobacter pylori vacuolating cytotoxin-producing strains (Tox+) were isolated from 14 (46.7%) patients, whereas non-cytotoxin-producing (Tox-) H. pylori strains were isolated from the remaining patients. Of 30 patients studied, 20 (66.7%) had serum cytotoxin neutralizing activity in vitro. Fourteen patients with Tox+ H. pylori strains showed serum cytotoxin neutralizing activity and serum immunoglobulin G (IgG) and IgA antibodies reactive with both 87-kDa H. pylori vacuolating cytotoxin (VacA) and 128-kDa cytotoxin-associated gene product (CagA) by immunoblotting using native enriched preparations of VacA and CagA proteins from H. pylori culture supernatants as the antigens. A 94-kDa antigen cross-reacting with the 87-kDa VacA protein could be demonstrated in culture supernatant with immune sera from humans and animals. All patients (n = 10) lacking serum neutralizing activity were also negative for IgG or IgA against VacA antigen, whereas 6 of the 10 patients showed IgG serum antibody responses against CagA antigen. The prevalence of antibodies to VacA and CagA antigens was significantly (P < 0.001) higher in patients with gastritis (20 and 26 patients for VacA and CagA, respectively, of 30 patients) than in H. pylori culture-negative controls (0 of 27 for both VacA and CagA) and in randomly selected blood donors (17 and 21 for VacA and CagA, respectively, of 120 subjects). All patients with PUD had antibodies to CagA, whereas 13 of 17 (76.5%) patients with NUD had anti-CagA antibodies. Serum IgG antibodies to VacA were present in 9 (69.2%) patients with PUD of 13 patients and in 11 (64.7%) patients with NUD of 17 patients. Anti-CagA antibodies seemed to correlate better with PUD than anti-VacA antibodies.  相似文献   

16.
Helicobacter pylori infects the majority of the population in the developing countries. However, the rate of gastrointestinal complications such as peptic ulcers and gastric malignancies has no parallel with the infection. In order to determine whether cytotoxin (vacA) and its allelic polymorphism can serve as screening markers for such a population, H. pylori strains were isolated from one hundred and thirty two dyspeptic patients. H. pylori genomic DNA was extracted and underwent PCR-amplification for the cytotoxin alleles. Genotyping of the signal sequence region of the vacA gene identified 68% (70 out of 103) of patients with non ulcer dyspepsia (NUD) and 79% (23 out of 29) of the patients with peptic ulcer disease (PUD) possessing the s1 genotype. S1 strains were significantly more prevalent among patients with PUD as compared to the NUD (p < 0.05). In regard to the middle region, 55% of the patient isolates belonged to the m2 genotype with no correlation to disease. The s1m2 genotype was the most prevalent among all patients and significantly correlated with the PUD group (p < 0.05).  相似文献   

17.
Since the methods for metronidazole susceptibility testing of Helicobacter pylori have not been standardized or validated, we compared three methods that are used to test the metronidazole susceptibilities of 25 isolates of H. pylori. Specifically, we examined the methods of Steer's replicator agar dilution, tube broth microdilution, and modified Kirby-Bauer disk diffusion. The metronidazole disk zone sizes obtained by the disk diffusion method correlated well (r = 0.74) with the MICs obtained by the agar dilution method. Afterward, the disk diffusion method was used to characterize the metronidazole susceptibilities of 44 isolates of H. pylori. Dual therapy (bismuth and metronidazole) proved to be highly effective against metronidazole-susceptible strains (81.6% eradication rate) but fared poorly against resistant strains (16.7% eradication rate; P < 0.01). Using agar dilution testing, we validated the modified Kirby-Bauer disk diffusion method for metronidazole susceptibility testing of H. pylori and conclude that it is practical, accurate, and clinically applicable.  相似文献   

18.
The aim of this study was to determine the susceptibilities to clarithromycin, amoxycillin and metronidazole of Helicobacter pylori isolates from the antrum and corpus of Japanese patients examined during the period 1995-2001. There was an increase, from 6.2% in 1995 to 22.1% in 2000-2001, in the proportion of patients infected with clarithromycin-resistant H. pylori. Of patients infected with clarithromycin-resistant H. pylori, 39.1% were infected with both clarithromycin-susceptible and -resistant H. pylori. Furthermore, the MIC90 of clarithromycin for H. pylori rose from < 1 mg/L in 1995-1998 to 8 mg/L in 1999. In contrast, the MIC90s of amoxycillin and metronidazole were < or = 0.125 and 4 mg/L, respectively, throughout the study period. The results showed that, while most H. pylori isolates were susceptible to amoxycillin and metronidazole, resistance to clarithromycin among H. pylori isolates increased markedly in Japan during 1995-2001. The results also indicated a need to test the susceptibility of H. pylori isolates from more than two samples obtained from two different sites in the stomach of a single patient in order to diagnose the presence of clarithromycin-resistant H. pylori correctly.  相似文献   

19.
The aim of the study was to evaluate the prevalence of resistance to amoxicillin, metronidazole, and clarithromycin before treatment of Helicobacter pylori infection in children and to assess the evolution of resistance with time. The study was carried out between 1994 and 1999 with 150 H. pylori-positive children through gastric culture (antimicrobial susceptibility) and histology. All cultured H. pylori strains were sensitive to amoxicillin, 64 (43%) were resistant to metronidazole, 32 (21%) were resistant to clarithromycin, and 14 (9%) were resistant to both metronidazole and clarithromycin. The overall prevalence of resistance to metronidazole and clarithromycin did not change significantly with time. The study highlights the generalized high-level and stable metronidazole and clarithromycin resistance of H. pylori strains from children.  相似文献   

20.
Background: Helicobacter pylori has become recognized as a major cause of gastroduodenal diseases in man. Evidence indicates that once acquired, H. pylori persists, usually for life unless eradicated by antimicrobial therapy. Over the past few years, we have accumulated some knowledge of the epidemiology of H. pylori in Ile-Ife, South-West Nigeria. In one collaborative study, we detected H. pylori in 195 (73%) patients referred for endoscopy at Obafemi Awolowo University Teaching Hospitals Complex (OAUTHC). Furthermore we have observed a variegated gastric inflammatory response and atrophy including atrophic pangastritis but are yet to demonstrate MALToma in any of our patients. In addition we have demonstrated that dental plaque is a possible source of gastric H. pylori infection and such an endogenous source could account for difficulty in eradication leading to re-infection. Presently, infected patients are treated with standard combination therapy made up of amoxycilin and ciprofloxacin with a proton pump inhibitor/bismuth. Reports however have shown that the incidence of antimicrobial resistance in Helicobacter pylori is a growing problem and which has been linked with failures in treatment and eradication. Given this situation it has become necessary to have information about the susceptibility of isolates to particular antimicrobial agents before the selection of an appropriate treatment regimen. Objectives: More recently, we sought to study antimicrobial susceptibility of locally isolated H. pylori strains. Methods: We subjected 32 isolates to antimicrobial susceptibility testing against seven agents. Results: All the isolates showed multiple acquired antimicrobial resistance as they were all resistant to amoxicillin, clarithromycin, metronidazole, while 29/31, 27/31 showed resistance to rifampicin and tetracycline respectively. Five (15.6%) of these isolates showed resistance to ciprofloxacin. Conclusions: Our findings suggest that H. pylori strains isolated within our study environment have acquired resistance to all the commonly prescribed antibiotics. On the basis of the findings it would be necessary to re-evaluate the eradication treatment regime in our setting.  相似文献   

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